Reconstituted tobacco and preparation method thereof

ABSTRACT

The present invention provides reconstituted tobacco and a preparation method thereof, and belongs to the technical field of tobacco. The preparation method provided by the present invention includes the steps of: subjecting tobacco stems to hot-water extraction and pulping by mill successively to obtain tobacco stem pulp; mixing the tobacco stem pulp with alkaline matter for oxygen delignification in an oxygen environment to obtain oxygen-delignified tobacco stem pulp, where the alkaline matter includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate; mixing the oxygen-delignified tobacco stem pulp with tobacco pulp, calcium carbonate and a retention agent, and subjecting the mixture to a papermaking process in the paper machine to obtain reconstituted tobacco sheets; and coating the reconstituted tobacco sheets with a concentrated tobacco extracting solution to obtain reconstituted tobacco. By means of the oxygen delignification of the tobacco stem pulp in the present invention, the lignin component in tobacco stems is partially removed, and the reconstituted tobacco prepared from processed tobacco stems and other raw materials has a soft flavor without wood smell.

TECHNICAL FIELD

The present invention relates to the technical field of tobacco, in particular to reconstituted tobacco and a preparation method thereof.

BACKGROUND

Currently, the most common process for the production of reconstituted tobacco is by the papermaking process. Compared with tobacco, reconstituted tobacco is made from complex and diverse raw materials including tobacco stems, tobacco powder, tobacco fragments, waste tobacco and additional vegetable fibers. Tobacco stems account for a large proportion during the production of reconstituted tobacco by papermaking process. Tobacco stems are processed as below: placing tobacco stems in hot water to extract water-soluble matter and then separating thick tobacco stems into fibers in the pulping (by disc mill) manner to facilitate molding in the paper machine. Tobacco stems, different from tobacco, refer to stems of tobacco and contain a high content of lignin. The above pulping manner utilizes a mechanical process to obtain pulp and almost all the lignin is retained in the tobacco stem pulp in the process. The phenolic structures in the lignin will produce wood and paper-burning smells during the combustion of cigarettes, leading to a poor sensory quality of reconstituted tobacco.

SUMMARY

In this regard, the present invention aims to provide reconstituted tobacco and a preparation method thereof. The tobacco obtained by the preparation method of the present invention preferably has a soft flavor without a wood smell, or at least only a slight wood smell.

The present invention provides a method for preparing reconstituted tobacco, including the following steps:

1) subjecting tobacco stems to hot-water extraction and pulping by mill successively to obtain tobacco stem pulp;

2) mixing the tobacco stem pulp obtained in step 1) with alkaline matter for oxygen delignification in an oxygen environment to obtain oxygen-delignified tobacco stem pulp, where the alkaline matter includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate;

3) mixing the oxygen-delignified tobacco stem pulp obtained in step 2) with tobacco pulp, wood pulp fibers, calcium carbonate and a retention agent, and subjecting the mixture to a papermaking process in the paper machine to obtain reconstituted tobacco sheets; and

4) coating the reconstituted tobacco sheets obtained in step 3) with a concentrated tobacco extracting solution to obtain reconstituted tobacco.

Preferably, for the hot-water extraction in step 1), the temperature is 40-70° C. and the duration is 30-120 min.

Preferably, in step 1), the moisture content of the tobacco stem pulp is 10-30 wt %.

Preferably, for the oxygen delignification in step 2), the temperature is 90-120° C., the duration is 5-30 min and the pressure is 0.4-0.8 MPa.

Preferably, the mass of the alkaline matter in step 2) is 2-20% of that of the tobacco stems in step 1).

Preferably, in step 2), the concentration of the oxygen-delignified tobacco stem pulp is 10-25 wt %.

Preferably, in step 3), the concentration of the tobacco pulp is 5-15 wt %.

Preferably, in step 3), the mass ratio of the oxygen-delignified tobacco stem pulp to the tobacco pulp is 1:1; the usage of wood pulp fibers, calcium carbonate and the retention agent is respectively 16-25%, 10-20% and 0.1-0.3% of the total mass of the oxygen-delignified tobacco stem pulp and the tobacco pulp.

Preferably, in step 4), the concentration of the concentrated tobacco extracting solution is 35-50 wt %.

The present invention further provides the reconstituted tobacco obtained by the above-described preparation method.

The beneficial technical effects are as follows: the present invention provides reconstituted tobacco and a preparation method thereof, where the preparation method includes the steps of: subjecting tobacco stems to hot-water extraction and pulping by mill successively to obtain tobacco stem pulp; mixing the tobacco stem pulp with alkaline matter for oxygen delignification in an oxygen environment to obtain oxygen-delignified tobacco stem pulp, where the alkaline matter includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate; mixing the oxygen-delignified tobacco stem pulp with tobacco pulp, calcium carbonate and a retention agent, and subjecting the mixture to a papermaking process in the paper machine to obtain reconstituted tobacco sheets; and coating the reconstituted tobacco sheets with a concentrated tobacco extracting solution to obtain reconstituted tobacco. By means of the oxygen delignification of the tobacco stem pulp in the present invention, the lignin component in tobacco stems is partially removed, and the reconstituted tobacco prepared from processed tobacco stems and other raw materials has a soft flavor without a wood smell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flowchart of a preferred method for preparing reconstituted tobacco provided by the present invention.

DETAILED DESCRIPTION

The present invention provides technical benefits and a preparation method thereof, where the preparation method includes the following steps:

1) subjecting tobacco stems to hot-water extraction and pulping by mill successively to obtain tobacco stem pulp;

2) mixing the tobacco stem pulp obtained in step 1) with alkaline matter for oxygen delignification in an oxygen environment to obtain oxygen-delignified tobacco stem pulp, where the alkaline matter includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate;

3) mixing the oxygen-delignified tobacco stem pulp obtained in step 2) with tobacco pulp, calcium carbonate and a retention agent, and subjecting the mixture to a papermaking process in the paper machine to obtain reconstituted tobacco sheets; and

4) coating the reconstituted tobacco sheets obtained in step 3) with a concentrated tobacco extracting solution to obtain reconstituted tobacco.

In the present invention, the tobacco stems are subjected to hot-water extraction and pulping by mill successively to obtain tobacco stem pulp.

In the present invention, the temperature of the hot-water extraction is preferably 40-70° C. and more preferably 50-60° C.; the duration of the hot-water extraction is preferably 30-120 min, more preferably 50-100 min, and most preferably 60-80 min.

In the present invention, after the hot-water extraction, the method also includes pressing the tobacco stems until the moisture content is preferably 70-90 wt % and more preferably 80-85 wt %. The present invention imposes no specific limitation on the pressing method in the present invention, and any pressing method well known to those skilled in the art may be chosen. In the present invention, a screw extruder is preferably used.

The present invention imposes no specific limitation on the pulping method in the present invention, and any pulping method well known to those skilled in the art may be chosen. In the present invention, a disc mill is preferably used.

In the present invention, the moisture content of the tobacco pulp is preferably 10-30 wt % and more preferably 15-25 wt %. The present invention imposes no specific limitation on the method for adjusting the moisture content of the post-pulping tobacco stem pulp in the present invention, and any method well known to those skilled in the art may be chosen.

After the tobacco stem pulp is obtained, the present invention mixes the tobacco stem pulp with alkaline matter for oxygen delignification in an oxygen environment to obtain oxygen-delignified tobacco stem pulp, where the alkaline matter includes one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate.

In the present invention, the alkaline matter is preferably one or more of potassium carbonate, sodium carbonate and sodium bicarbonate. Where the alkaline matter is a mixture of two or more substances, the present invention imposes no specific limitation on the proportions of the alkaline substances in the mixture, and any proportions may be adopted. In the present invention, the mass of the alkaline matter is preferably 2-20% of that of the tobacco stems, more preferably 5-15% and most preferably 10%.

In the present invention, the temperature of the oxygen delignification is preferably 90-120° C. and more preferably 100-110° C.; the duration of the oxygen delignification is preferably 5-30 min, more preferably 10-25 min and most preferably 15-20 min; the pressure of the oxygen delignification is preferably 0.4-0.8 MPa and more preferably 0.5-0.6 MPa.

In the present invention, after the oxygen delignification, the method also preferably includes washing and concentrating the pulp after oxygen delignification to obtain oxygen-delignified tobacco stem pulp.

In the present invention, 10-50 wt % of lignin fibers in the tobacco stems can be removed by oxygen delignification.

The present invention imposes no specific limitation on the pulp washing method in the present invention, and any pulp washing method well known by those skilled in the art may be chosen. In the present invention, a pulp washing machine is preferably used. In the present invention, the lignin and residual alkaline matter in the pulp are removed by pulp washing.

The present invention imposes no specific limitation on the concentration method in the present invention, and any concentration method well known by those skilled in the art may be chosen. In the present invention, a decker is preferably used for concentration. The concentration of the oxygen-delignified tobacco stem pulp after concentration is preferably 10-25 wt % and more preferably 15-20 wt %.

After oxygen-delignified tobacco stem pulp is obtained, the present invention mixes the oxygen-delignified tobacco stem pulp with tobacco pulp, calcium carbonate and a retention agent, and subjects the mixture to a papermaking process in the paper machine to obtain reconstituted tobacco sheets.

In the present invention, the concentration of the tobacco pulp is preferably 5-15 wt % and more preferably 10 wt %.

In the present invention, the retention agent is preferably cationic guar gum or chitosan; the usage of the retention agent is preferably 0.1-0.3% of the mass of the absolutely dry oxygen-delignified tobacco stem pulp, and more preferably 0.15%.

In the present invention, the mass ratio of the oxygen-delignified tobacco stem pulp to the tobacco pulp is preferably 1:1; the usage of wood pulp fibers, calcium carbonate and the retention agent is respectively 16-25%, 10-20% and 0.1-0.3% of the total mass of the oxygen-delignified tobacco stem pulp and the tobacco pulp.

In a preferred embodiment of the present invention, the mass per unit area of the reconstituted tobacco sheets is preferably 58-62 g/m² and more preferably 60 g/m².

The present invention imposes no specific limitation on the specific papermaking process in the paper machine, and any papermaking process well known to those skilled in the art may be chosen.

After reconstituted tobacco sheets are obtained, the present invention coats the reconstituted tobacco sheets with a concentrated tobacco extracting solution to obtain reconstituted tobacco.

In the present invention, the concentrated tobacco extracting solution is preferably the liquid obtained by concentrating the pressed liquid-phase component to 35-50 wt %.

In the present invention, the concentration of the concentrated tobacco extracting solution is preferably 35-50 wt % and more preferably 40-45 wt %.

In the present invention, the coating weight of the concentrated tobacco extracting solution in the coating process is preferably 30-60 g/m² and more preferably 40-50 g/m². The present invention imposes no specific limitation on the specific coating operation method in the present invention, and any operation method well known by those skilled in the art may be chosen.

FIG. 1 is a schematic flowchart of the method for preparing reconstituted tobacco provided by the present invention.

The present invention further provides the reconstituted tobacco obtained by the above preparation method.

For the purpose of better understanding, the present invention will be further illuminated below through description of preferred embodiments. However, the present invention will not be limited by the following preferred embodiments.

Preferred Embodiment 1

1) 150 kg of tobacco stems are subjected to hot-water extraction at 40° C., are pressed by the screw extruder until the moisture content is 70%, and are pulped by the disc mill, so that 500 kg of tobacco stem pulp with a 15% mass concentration is obtained.

2) The tobacco stem pulp obtained in step 1) and 15% sodium carbonate (in relation to the mass of the absolutely dry tobacco stems) are mixed for oxygen delignification for 20 min in an oxygen environment where the temperature is 120° C. and the pressure is 0.6 MPa, and the pulp after oxygen delignification is subjected to washing and concentration to obtain oxygen-delignified tobacco stem pulp with a 10% mass concentration.

3) 50 parts of oxygen-delignified tobacco stem pulp obtained in step 2), 50 parts of tobacco pulp, 20 parts of wood pulp fibers, 15 parts of calcium carbonate and 0.15% of cationic guar gum (in relation to the absolutely dry pulp) as a retention agent are mixed, and the mixture is subjected to a papermaking process in the paper machine to obtain reconstituted tobacco sheets with 60±2 g/m².

4) The reconstituted tobacco sheets obtained in step 3) are coated with a concentrated tobacco extracting solution to obtain reconstituted tobacco, where the coating weight is 40 g/m².

The evaluations of the lignin content of the oxygen-delignified tobacco stem pulp, the physical properties of the sheets and the sensory quality of the reconstituted tobacco in preferred embodiment 1 are provided as follows:

TABLE 1 Evaluations of lignin content of oxygen-delignified tobacco stem pulp, properties of sheets and sensory quality of reconstituted tobacco in preferred embodiment 1 Tobacco stems without oxygen Oxygen-delignified Indicators delignification tobacco stems Lignin content 20.91 13.59 of tobacco stems, % Bulk of reconstituted 2.08 2.05 tobacco sheets, cm³/g Tensile index of 11.06 12.72 reconstituted tobacco sheets, N · m/g Softness of reconstituted tobacco sheets, TS7 (Tissue Softness 97.6 77.3 Analyzer (TSA), German Emtec Company) Lower softness means better softness Evaluation of sensory Paper-burning smell, Soft flavor, no wood quality of strong wood smell, smell reconstituted tobacco offensive odor

As seen from Table 1, the lignin content of the oxygen-delignified tobacco stems is reduced. When the bulk of the reconstituted tobacco is basically the same, the reconstituted tobacco sheets after oxygen delignification are higher in tensile index and better in softness, and the reconstituted tobacco have a soft flavor, no wood smell and a high sensory-quality evaluation.

Preferred Embodiment 2

1) 150 kg of tobacco stems are subjected to hot-water extraction at 70° C., are pressed by the screw extruder until the moisture content is 90%, and are pulped by the disc mill, so that 500 kg of tobacco stem pulp with a 10% mass concentration is obtained.

2) The tobacco stem pulp obtained in step 1), 15% of sodium carbonate (in relation to the mass of the absolutely dry tobacco stems) and 1.0% of magnesium sulfate (in relation to the mass of the absolutely dry tobacco stems) are mixed for oxygen delignification for 20 min in an oxygen environment where the temperature is 120° C. and the pressure is 0.6 MPa, and the pulp after oxygen delignification is subjected to washing and concentration to obtain oxygen-delignified tobacco stem pulp with a 10% mass concentration.

3) 50 parts of oxygen-delignified tobacco stem pulp obtained in step 2), 50 parts of tobacco pulp, 20 parts of wood pulp fibers, 15 parts of calcium carbonate and 0.15% cationic guar gum (in relation to the absolutely dry pulp) as a retention agent are mixed, and the mixture is subjected to a papermaking process in the paper machine to obtain reconstituted tobacco sheets with 60±2 g/m².

4) The reconstituted tobacco sheets obtained in step 3) are coated with a concentrated tobacco extracting solution to obtain reconstituted tobacco, where the coating weight is 40 g/m².

The evaluations of the lignin content of the oxygen-delignified tobacco stem pulp, the physical properties of the sheets and the sensory quality of the reconstituted tobacco in preferred embodiment 2 are provided as follows:

TABLE 2 Evaluations of lignin content of oxygen-delignified tobacco stem pulp, properties of sheets and sensory quality of reconstituted tobacco in preferred embodiment 2 Tobacco stems without oxygen Oxygen-delignified Indicators delignification tobacco stems Lignin content 20.91 15.7 of tobacco stem fibers, % Bulk of 2.08 2.06 reconstituted tobacco sheets, cm³/g Tensile index of 11.06 11.60 reconstituted tobacco sheets, N · m/g Softness of 97.6 84.5 reconstituted tobacco sheets Evaluation of Paper-burning smell, Soft flavor, slight wood smell sensory strong wood smell, quality of offensive odor reconstituted tobacco

As seen from Table 2, the lignin content of the oxygen-delignified tobacco stems is reduced. When the bulk of the reconstituted tobacco is basically the same, the reconstituted tobacco sheets after oxygen delignification are higher in tensile index and lower and better in softness, and the reconstituted tobacco has a soft flavor, only a slight wood smell and a high sensory-quality evaluation.

Preferred Embodiment 3

1) 150 kg of tobacco stems are subjected to hot-water extraction at 50° C., are pressed by the screw extruder until the moisture content is 80%, and are pulped by the disc mill so that 500 kg of tobacco stem pulp with a 25% mass concentration is obtained.

2) The tobacco stem pulp obtained in step 1), 20% of sodium carbonate (in relation to the mass of the absolutely dry tobacco stems) and 1.0% of magnesium sulfate (in relation to the mass of the absolutely dry tobacco stems) are mixed for oxygen delignification for 20 min in an oxygen environment where the temperature is 120° C. and the pressure is 0.6 MPa, and the pulp after oxygen delignification is subjected to washing and concentration to obtain oxygen-delignified tobacco stem pulp with a 10% mass concentration.

3) 50 parts oxygen-delignified stem pulp obtained in step 2), 50 parts of tobacco pulp, 20 parts of wood pulp fibers, 15 parts of calcium carbonate and 0.15% cationic guar gum (in relation to the absolutely dry pulp) as a retention agent are mixed, and the mixture is subjected to a papermaking process in the paper machine to obtain reconstituted tobacco sheets with 60±2 g/m².

4) The reconstituted tobacco sheets obtained in step 3) are coated with a concentrated tobacco extracting solution to obtain reconstituted tobacco, where the coating weight is 40 g/m².

The evaluations of the lignin content (Klason lignin) of the oxygen-delignified tobacco stem pulp, the physical properties of the sheets and the sensory quality of the reconstituted tobacco in preferred embodiment 3 are provided as follows:

TABLE 3 Evaluations of lignin content of oxygen-delignified tobacco stem pulp, properties of sheets and sensory quality of reconstituted tobacco in preferred embodiment 3 Tobacco stems without oxygen Oxygen-delignified Indicators delignification tobacco stems Lignin content of 20.91 9.82 tobacco stem fibers, % Bulk of 2.08 2.01 reconstituted tobacco sheets, cm³/g Tensile index of 11.06 13.28 reconstituted tobacco sheets, N · m/g Softness of 97.6 65.9 reconstituted tobacco sheets Evaluation of Paper-burning smell, Soft flavor, no wood smell sensory strong wood smell, quality of offensive odor reconstituted tobacco

As seen from Table 3, the lignin content of the oxygen-delignified tobacco stems is reduced. When the bulk of the reconstituted tobacco is basically the same, the reconstituted tobacco sheets after oxygen delignification are higher in tensile index and lower and better in softness, and the reconstituted tobacco has a soft flavor, no wood smell and a high sensory-quality evaluation.

The foregoing descriptions are only preferred embodiments of the present invention. It should be noted that for a person of ordinary skill in the art, several improvements and modifications may further be made without departing from the principle of the present invention. These improvements and modifications should also be deemed as falling within the protection scope of the present invention. 

What is claimed is:
 1. A method for preparing reconstituted tobacco, comprising the following steps: 1) subjecting tobacco stems to hot-water extraction and pulping by mill successively to obtain tobacco stem pulp; 2) mixing the tobacco stem pulp obtained in step 1) with alkaline matter for oxygen delignification in an oxygen environment to obtain oxygen-delignified tobacco stem pulp, wherein the alkaline matter comprises one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate and sodium bicarbonate; 3) mixing the oxygen-delignified tobacco stem pulp obtained in step 2) with tobacco pulp, wood pulp fibers, calcium carbonate and a retention agent resulting in a mixture, and subjecting the mixture to a papermaking process in a paper machine to obtain reconstituted tobacco sheets; and 4) coating the reconstituted tobacco sheets obtained in step 3) with a concentrated tobacco extracting solution to obtain reconstituted tobacco.
 2. The preparation method according to claim 1, wherein the hot-water extraction in step 1) is carried out at a temperature of 40-70° C. and for a duration of 30-120 min.
 3. The preparation method according to claim 1, wherein in step 1), the tobacco stem pulp has a moisture content of 10-30 wt %.
 4. The preparation method according to claim 1, wherein for the oxygen delignification in step 2) is carried out at a temperature of 90-120° C., for a duration of 5-30 min and a pressure of 0.4-0.8 MPa.
 5. The preparation method according to claim 1, wherein the alkaline matter in step 2) has a mass that is 2-20% of that of the tobacco stems in step 1).
 6. The preparation method according to claim 1, wherein in step 2), the oxygen-delignified tobacco stem pulp has a concentration of 10-25 wt %.
 7. The preparation method according to claim 1, wherein in step 3), the tobacco pulp has a concentration of 5-15 wt %.
 8. The preparation method according to claim 1, wherein in step 3), a mass ratio of 1:1 exists between the oxygen-delignified tobacco stem pulp and the tobacco pulp; and the usage of wood pulp fibers, calcium carbonate and the retention agent is respectively 16-25%, 10-20% and 0.1-0.3% of the total mass of the oxygen-delignified tobacco stem pulp and the tobacco pulp.
 9. The preparation method according to claim 1, wherein in step 4), the concentrated tobacco extracting solution has a concentration of 35-50 wt %.
 10. The reconstituted tobacco obtained by the preparation method described in claim
 1. 11. The reconstituted tobacco obtained by the preparation method described in claim
 2. 12. The reconstituted tobacco obtained by the preparation method described in claim
 3. 13. The reconstituted tobacco obtained by the preparation method described in claim
 4. 14. The reconstituted tobacco obtained by the preparation method described in claim
 5. 15. The reconstituted tobacco obtained by the preparation method described in claim
 6. 16. The reconstituted tobacco obtained by the preparation method described in claim
 7. 17. The reconstituted tobacco obtained by the preparation method described in claim
 8. 18. The reconstituted tobacco obtained by the preparation method described in claim
 9. 